/*
 * The MIT License
 *
 * Copyright 2014 David Rodenas Pico.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package edu.uoc.sd.fr14.model;

/**
 * This class computes if there is enough quorum to approve a modification operation.
 * <p>
 * 
 * It is obtained by the Cluster and used internally by {@link Log#prepared(OpId, Quorum)}
 * in order to know if an operation can be safely executed and stored in the log.
 *
 * @author drodenas
 */
public final class Quorum {

    public static Quorum createFromTotal(int count) {
        if (count < 0) throw new IllegalArgumentException("Illegal argument: count cannot be null");
        
        return new Quorum(count / 2);
    }
    
    private final int quorum;

    private Quorum(int quorum) {
        assert quorum > 0;
        
        this.quorum = quorum;
    }

    @Override
    public String toString() {
        return "Qu="+quorum;
    }

    boolean isOverflow(int count) {
        return count > quorum;
    }
    
    boolean satisfies(int count) {
        //assert !isOverflow(count);
        
        return count == quorum;
    }
    
    
}
